Field of the Invention
Manipulators on mobile robots require specialized end effectors (tools/components) in order to accomplish particular missions. Currently, deployed systems have end effectors designed, built, and installed at the factory. Factory installed tools can only be repaired or replaced in a factory. This limits the effectiveness of the robot to those missions which can be achieved with a single tool. Heretofore, when a new candidate task is identified, the typical response has been to design and build a new robot intended to perform the specific task. Sometimes existing unmanned ground vehicles (UGV) platforms are used, but just as often, a new robot is created to specifically address the task. This has resulted in a proliferation of small UGVs, each performing admirably on tasks within each of its subset of core competencies, but is generally unsuitable for tasks that vary too widely from its essential purpose. It is impractical to expect field teams to carry multiple UGVs, each suited for a specific task. In addition to the strain on the physical resources of the field team (e.g., transportation and maintenance), different robots come with different control schemes. This reduces the ability of the operator to capitalize on the experience and intuition gained from operating previous robots, because the operator cannot rely on the trained reflexes developed while controlling previous robots. In fact, these differing control schemes lead to operator errors and inefficient control.
Another approach has been to design new, more capable robots, but this approach has drawbacks because even if a robot were designed and built to perform all of the tasks currently assigned to UGVs, it would quickly become outdated as new tasks and jobs are identified. Additionally, external variables, such as physical environment, make UGVs designed for one environment wholly impractical for use in another environment, meaning a number of new robot types would need to be designed, tested, and built. Systems with replaceable end effectors are also ineffective because they require a technician and possibly a number of specialty tools. Generally, these changes would require a technician to remove the current tool and to attach its replacement. This may involve physically disconnecting the tool, disconnecting electrical connections, physically attaching the new tool, and hooking up its electrical connections. The system may also require reconfiguring the control software for each specialized tool. Particularly, in time critical applications, such as military or civilian Explosives Ordinance Disposal (EOD), this process is too slow and interferes with missions.
Military and law enforcement groups are increasingly relying on UGVs to perform life-threatening tasks ranging from under car inspection to EOD. As small UGVs, such as Omni-Directional Inspection Systems (ODIS), Talon and Packbot have gained acceptance, the variety of tasks they have been required to perform has increased. Drive systems utilize significant power, unlike industrial robots, these systems are deployed in uncontrolled environments. Driving a system back and forth to physically disconnect a tool is impractical. Operators can stand more than 300 meters from a site. It can take valuable time and resources to drive a robot away in the course of action.
In addition, it takes a robust design to survive the normal working environment for such devices, both during deployment on the mobile robot and when the manipulator and tools are being stored or transported. Mechanical connections must be compliant to minor variations in manufacturing tolerances of mating components, or environmental tolerances which develop when a tool is dropped or bumped against another tool in the toolbox, or caused by the presence of debris, such as dirt and sand, captured from the working environment.
Robotic arms often require specialized configurations to accomplish their particular mission, requiring change in the length of a link in the arm or attaching a different end effector or tool.
Tools that attach to links of the robotic arm that are pivoting or rotating must be able to withstand the large bending movements and torques that result from this.
An object of the present invention is to provide an automated tool change assembly for separating robotic end effectors mechanically from their manipulator arms during deployment, thus allowing unhindered integration of end effectors as the complexity.
Description of Related Art